If you are in one of those countries that Google Now is not yet supported in, you have the latest Google Search application installed on your iOS device, and you are jailbroken, you can head over to Cydia right now and pick up a new free jailbreak tweak called GoogleNowEnabler by iOS developer omokas.

GoogleNowEnabler enables Google Now via the Google Search application in countries that it is not yet supported out of the box. The tweak doesn't come with any options to configure, as it is basically one of those install-and-go type of jailbreak tweaks.

Using the tweak requires that you have the latest version (3.0) of the Google Search application installed on your iOS device. If you don’t have it yet, you can download it for free from this App Store link. You will find the GoogleNowEnabler tweak in Cydia's ModMyi repository at no cost.